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Aggregation & path information [was: 200K prefixes - Weekly Routing Table Report]

  • From: Patrick W. Gilmore
  • Date: Fri Oct 13 15:21:00 2006

On Oct 13, 2006, at 3:04 PM, Philip Smith wrote:

I was kinda hoping that it would hit 200K on Tuesday, then I could have
added the announcement to my aggregation recommendations lightning talk!
;-) Bit sad that a 200K table can be aggregated down to 109k prefixes
with no loss of path information (in my BGP table view).
I find this interesting.

Obviously the table contains kruft. But I know we could not shrink it to 109K prefixes without losing something from where I sit. Are you sure there's no additional path info?

If there were a way to guarantee certain prefixes are completely superfluous, we could make a hit list of just those providers, then ridicule or filter or cause them pain in some way to make them stop causing us pain. I haven't seen that type of report posted publicly, just "this CIDR can fit in that one" without actual guarantees that _paths_ are equivalent. (Usually the origin AS is matched as well as the prefixes, but that's not the same as guaranteeing the path is equivalent.)

Of course, this is non-trivial. But then neither is aggregating the global table. :)